Integrated circuits have evolved into complex devices that include millions of transistors, capacitors, and resistors on a single chip. The evolution of chip design continually requires faster circuitry and greater circuit density demanding increasingly precise fabrication processes. The precision processing of substrates requires precise control of temperature, rate, and pressure in the delivery of fluids used during processing.
Chemical vapor deposition (CVD) and atomic layer deposition (ALD) are two deposition processes used to form or deposit various materials on a substrate. In general, CVD and ALD processes involve the delivery of gaseous reactants to the substrate surface where a chemical reaction takes place under temperature and pressure conditions favorable to the thermodynamics of the reaction.
Many such deposition processes utilize a heated vessel or canister, such as an ampoule or bubbler, which contains a volatile liquid precursor under conditions conducive to vaporize the precursor. However, a common problem with the deposition of thin films is that many precursors have limited stability inside the ampoule. This is especially the case with metal precursors having low coordination number, as the metal center is more vulnerable to reaction with other compounds. The complex may react with impurities, decomposition products, or even the metal surface of the ampoule itself. Without increasing stability of the precursors, throughput of the deposition tool is diminished, or, worse yet, the process conditions may need to be completely re-engineered to inhibit decomposition and/or unwanted reactions. Accordingly, there is a need for additional apparatuses and methods of stabilizing metal precursors.